For manufacturing an electromagnet for use in a relay, winding operation of coil on a coil bobbin is executed such that after the coil bobbin is externally fitted onto the iron core, the end of the iron core projected out of a flange opening of the coil bobbin is held with a coil winding chuck device to be fixed considering the operation efficiency.
However, when the grasping degree of the iron core with the coil winding chuck device and the engagement degree of the coil bobbin and the iron core are not enough, there is a high possibility that the iron core is disengaged from the coil winding chuck device, the iron core and the coil bobbin are displaced, and the iron core is slipped out of the coil bobbin.
FIG. 10 is an explanatory view of a conventional coil winding operation. The reference numeral 120 is a coil bobbin having flange portions 121, 122 at both ends of a coil winding part 123 and the reference numeral 130 is an iron core comprising a head portion 131 and a body portion 132.
The coil bobbin 120 is externally fitted in such a manner that the head portion 131 of the iron core 130 and the other end 132a of the body portion 132 are projected out of the flange portion thereof 121, 122, respectively and a coil (not shown) is wound around the coil winding part 123 between the flange portions 121, 122. The reference numeral 124 represents an extended portion of the coil bobbin and is provided with a coil terminal 125.
Coil is wound when a rotary axis 112 connected to a grasping part 111 of the coil winding chuck device 110 is rotated under the condition of FIG. 10b. If the power of the grasping part 111 grasping the iron core 130 is weak, there is a possibility of disengagement of the iron core 130 out of the coil winding chuck device 110 as shown in FIG. 11a, FIG. 11b. In addition, when the coupling degree of the coil bobbin 120 and the iron core 130 is not enough, the iron core 130 and the coil bobbin 120 may be displaced or the iron core 130 may be slipped out of the coil bobbin 120.
Specifically in such a coil winding method, the object to be wound (coil bobbin, iron core) is rotated to wind coil while the end 132a of the iron core 130 is grasped so that there is a high possibility that the object to be wound is slipped out of the coil winding chuck device 110 by such a rotating operation.
In order solve such problems, many operational and technical attempts have been conventionally done such that the grasping power of the coil winding chuck device 110 is enlarged by a slip-proof member. However, such deficiency has not been surely prevented and specific preventive measures have been required for improving the structure of the object to be wound and the coil winding chuck device.